Surface coloration of perfluorohaloolefin polymers and colorant composition therefor



llnited States Patent 3,019,115 SURFACE COLORATION OF PERFLUOROHALO-OLEFIN POLYMERd AND COLORANT COMIO- SITION THEREFGR Herman S. Kaufman,Teaneck, and Fred W. West, Wayne,

N.J., assignors to Minnesota Mining and Manufacturing Company, St. Paul,MiHIL, a corporation of Delaware No Drawing. Filed July 23, 1958, Ser.No. 750,298 6 Claims. (Cl. 106-32) This invention relates to a processfor applying colorants to polymers of a perfluorohaloolefin. In oneaspect this invention relates to a process of applying colorants to thesurface of extruded polymers of trifluorochloroethylene, while in a moreparticular aspect this invention relates to a process of applying asolid, coloring material to the surface of extruded copolymers oftrifluoroc-hloroethylene and vinylidene fluoride. In another aspect thisinvention relates to the production of a colored coated wire. In stillanother important aspect this invention relates toa colorant compositionfor coloring perfluorohaloolefin polymers.

Because of their unusual chemical and physical characteristics thefluorine-containing thermoplastic polymers are widely used in numerousindustrial applications. Among the most outstanding of the properties offluorinecontaining thermoplastic polymers, such as polymers oftrifluorcchloroethylene, is chemical inertness. Thus, these polymers maybe exposed to a wide variety of oxidizing, and solvent-type reagents,such as fuming nitric acid, and fuels With no apparent effect on thepolymer. In addition to their high degree of chemical stability, thesepolymers possess high thermal stability, excellent electrical propertiesand may be molded or extruded into various useful items. Such polymersmay be extruded onto Wire to provide a coating or insulation ofparticularly useful properties. In many applications it is desirable tocolor such coating, as in the color coding of hookup wire, and variouscolorants may be incorporated into the polymer mixture prior toextrusion onto the wire. However, in such a coloring method thecolorants of pigments appear uniformly throughout the wire coating andtend to produce undesirable alterations in the physical properties ofthe coating Many pigments tend to alter the flow properties of themolten plastic during extrusion, each individual colorant tending torequire a different set of extrusion conditions for a given plastic.Furthermore, some pigments degrade the plastic almost to the point ofuselessness. When colorants are incorporated into the polymer beforeextrusion, a polymer loss as Well as a loss of time, i.e., in cleaningequipment, occurs when switching from one color to another. Occasionallythe residual colorant in the extruder will contaminate or discolorsubsequent runs of plastic of another color.

It is an object of this invention to provide a process for coloringperfluorohaloolefln plastics.

Another object of this invention is to provide a method for applyingpigments to extruded trifluorochloroethylene plastics.

Still another object of this invention is to provide a process forapplying pigments to the surface of extruded wire insulation.

A further object of this invention is to provide a coloring compositionfor perfluorohaloolefin plastics.

It is also an object of this invention to provide a process for coloringextruded trifluorochloroethylene plastics with a minimum amount ofcolorant and without altering the physical properties of the plastic.

Another object of this invention is to provide a process of coloringtrifluorochloroethylene plastics after the extrusion thereof.

According to this invention, specially formulated color- 3,019,115Patented Jan. 30, 1962 ant compositions comprising a heat and solventresistant colorant, trichloroethylene, and a polymer oftrifluorochloroethylene selected from the group consisting of oils,greases and Waxes, are applied to the surface of a perfluorohalooleflnpolymer and the colorant is set at a temperature above about 170 C. butbelow the decomposition temperature of the perfluorohaloolefin polymerbeing colored. The colorant setting operation can be accomplishedsimultaneously with the application of the colorant composition, or maybe accomplished subsequent to the application step, as is hereinafterdescribed.

Plastics which may be colored by the process of this invention arepolymers of perfluorohaloolefins, including both homopolymers andcopolymers thereof. Such polymers have been found to display outstandingproperties as wire insulation and may be blended or admixed in varyingproportions depending on the properties desired in the final coating.The homopolymers of perfluorohaloolefins which may be colored by theprocess of this invention may be prepared by the polymerization ofperfluorooleflns, such as tetrafluoroethylene, and ofperfluorochloroolefins such as trifluorochloroethylene, to produce athermoplastic material. The thermoplastic polymers oftrifluorochloroethylene generally have a N.S.T. above about 220 C.Copolymers of perfiuorohaloolefins which may be colored by the processof this invention may be prepared by the copolymerization oftetrafluoroethylene, perfluoropropene, and perfluorochloroolefins, suchas trifluorochloroethylene, and dichlorodifluoroethylene, with otherhalogenated olefins containing at least 2 hydrogen atoms per molecule,such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidenefluoride, and 1,1-fluorochloroethylene. Particularly suitable for wirecoating applications is the copolymer of trifluorochloroethylene andvinylidene fluoride, especially blends of various copolymers oftrifluorochloroethylene and vinylidene fluoride. It is a preferredembodiment of this invention to use as a wire coating a mixture of acopolymer of above but less than mol percent of trifluorochloroethyleneand less than 10 mol percent of vinylidene fluoride with at least onecopolymer of about 20 to about 69 mol percent triflurochloroethylene andabout 80 to about 31 mol percent of vinylidene fluoride. Three componentblends of these copolymers are particularly desirable.

The liquid or liquefiable polymers of trifluorochloroethylene, whichserve as vehicles in the ink of this invention are prepared bypolymerization of the monomer trifluorochloroethylene to produce oils,greases and soft waxes. Preferred vehicles are the oils or normallyliquid polymers since most marking processes are based on the use ofliquid composition. The greases and soft waxes are particularly suitedfor use in marking processes which require non-liquid compositions andfurther may be dissolved in solvents where liquid compositions arerequired. The greases and soft waxes have softening points below C. andpreferably below about 100 C. Usually, homopolymers of trifluoroethyleneare preferred since they are more readily applied to a wider variety ofmaterials. However, copolymers, in the oil, grease and soft Wax range,or trifluorochloroethylene copolymerized with halogenated olefins suchas vinyl chloride, vinyl fluoride, vinylidene fluoride,dichlorodifiuoroethy'lene, trifluoroethylene, etc. may also be used asvehicles and their use is within the scope of this invention.

A preferred liquid homopolymer of trifluorochloroethylone is that whichis generally known as telomer oil. The telomer oil is prepared bydirectly tclomerizing or polymerizing the monomertrifluorochloroethylene with a catalyst, such as benzoyl peroxide, inthe presence of sulfuryl chloride or bromohalomethane as the telogen toproduce a substantially saturated telomer oil. The telogen, such assulfuryl chloride, provides chlorine termi- "ice nal groups, tends tocontrol telomerization and terminates free radical reaction so that byvarying the amount of telogen used, the telomeric material may beobtained in the desired form, that is as an oil, grease or wax which isrecovered as the product of the process.

A; number of carbon atoms and of chlorine terminal groups. Those liquidhomopo'ymers or telomers, which are suitable to the process of thisinvention, contain between about 4 and about 15 monomer units in thechain or 8 to 30 carbon atoms. A typical analysis of the preferredliquid 5 The reaction occurs essentially as shown below: homopolymershows a chlorine content of 31.1% and a catalyst fluorine content of46.2%. The preparation of the above 7ZOF2= F 1+SO2o1z SOr+CI( rtelomeris described in detail in US. Patent 2,770,659 of As shown, sulfurdioxide gas is formed as well as a clear William S. Barnhart, issuedNovember 13, 1956. polymeric mass, usually in gel-like form, whichincludes 10 Liquid and liquefiable trifiuorochloroethylene polymersvarious grades of telomeric halocarbons, such as oils, may also beprepared by other methods, such. as by hlgh greases and soft waxes.These telomeric halocarbons temperature cracking of a high molecularweight trifluoromay be separated by conventional distillation. Thedischloroethylene polymer and stabilizing the resulting untillable,i.e., liquid and liquefiable, substances obtained by saturated crackedoil, as shown in US. Patent 2,636,907 telomerizlngchlorotrifiuoroethylene compounds in the of Miller, issued April 28,1953. presence of sulfuryl chloride are sufilciently stable as not Thereis a difierence between the various liquid and to absorb appreciableamounts of fluorine even though liquefiable homopolymers oftrifluorochloroethylene deexposed to the gas for 24 hours at atemperature of 60 pending upon the method by which they are prepared. C;or to significantly pyrolytically decompose at tempera- Thus, whileeither telomer oil or cracked oil may be used tures up to 200 C. Thisprocess may also be used to interchangeably in the colorant compositionfor marking prepare low molecular weight copolymers or cotelomersnon-fluorlnated thermoplastics, such as vinyl chloride, oftrifluorochloroethylene with halogenated olefins. vinylidene chloride,etc. noticeable differences in the The mol ratio of sulfuryl chloride tomonomer employed quality of the mark were observed with respect to thein these procedures is between about 2:1 and about 1:10, fiuorinatedthermoplastics. Generally, the more highly preferably between 1:1 and1:4 depending upon the prod- 25 fiuorinated plastics were lesssatisfactorily marked with ucts desired and the starting materials used.The optiinks which contained cracked oil as avehicle. mum mol' ratio-forproducing primarily-telomeric chloro- In the formation of the inks whichcomprise this intrifiuoroethylene oils and greases is 1:2 of the telogento vention, any suitable pigment, dye or lake may be emmonomer. Thetelomerization may be carried out in the ployed as the colorant. Theterm pigment as used herepresence of a suitable inert solvent, ifdesired. The term in includes dyes, lakes and. inorganic pigments. Thepiglneft Solvent mfians y q Whlch does not mlterlally ment may besoluble or insoluble in the vehicle and, if alter normal telomerllallon0f hf'illoethylenw insoluble, is preferably finely-divided and dispersedwithin pounds in the presence of sulfuryl chloride; such as Freon thewhich Any colored material may be used although, 113,tetrachloroethylene or tetrachloroethare. 1It should generally, organiccompounds are preferred over the line 'iotedlthgt wlalter slowldy reacts1with sulary g tg organic compounds because their colors are moreintense g i g gz 223 i i z f i ig g? and, therefore, less is required.Illustrative of the organic p e p a y pigments which may be employed arethe various phthaloanhydrous conditlons. Glass lined equipment isusually c amine aZo anthra uinone benzidene and r Clone desirable,however Monel and stainless steel have been H i. 1 1 bl R 32 t used forpolymerization and filtration apparatus without 4 en 1 0 par lcu ar ySu1.a e plgmen S 15 noticeable corrosion presented below in the table,although it 1s to be clearly The Preferred, liquid and liquefiablehomopolymers of understood that this list is representative and notunnecestrifluorochloroethylene made with sulfuryl chloride are Sanlyhmltmgr ThFSeIPIgmePtS are msoluble m the characterized by-the presencein the molecule of an even chloroethylene and m the Vehlcle- TABLECommon name 1 Referenceto Chemical name General structure structure InjPhthalocyanine blue. Karrers Organic Copper phthalocyaninePhthalocyanine pigment.

. Chemistry pp. Z8,7894th Edi,-

1011. Phthalocyanine green 1 Chlorinated copper-phthalocyanine Do. oHighly chlorinated copper-phthalocyanine Do. Benzidinc yellow ton I p.o-Dichlorobenzidine bis alpha-(azo o-methyl alpha-aceto acet-Substituted benzldine acetamanilide). ilide azo pigment. 5 .do .p.o-Dlchlorobenzidine bis alpha-(n20 alpha-acetoacetanilide) Do. 6 do p.o-Dichlorlogeizidine bis alpha-(azo o-p dimethyl-alphaeaceto- Do.

. acetanii e 7 -a- Dianisidineorangetonen p. o-Dianisidine bisalpha-(azo o-methyl-alpha acctoacetanilide).. Do. 8 V n. o p.o-Diansgdine bis alpha-(e20 o,p-dimethyl alpha-acetoacet- Do.

2.1111 G 9 do Fig; 62, p. 398... o-Diauisidine bis alpha-(azoalpha-acctoacetanilide) Do. 10.-., Lithosal red2'-B Fig. p. 412"...Calcium salt of Z-hydroxy-3-carboxy-l-naphthyl azo ortho-(p-Phenyl-naphthyl azo pigment.

3 ehlo ro-m-to1uene sulfonic acid). :Benzidmeorange toner" Fig. 51, p.392..... o-Dichlorobenzidine bis, 4-(azo-1-phenyl-3-methyl-pyrazolone)Substituted henzidine-pyrazoone azo i ment. .Vulcan fast redBA Fig: 81,p. 4070.-. io-Dichloil'obcpzidlne bis -(azo-l-phenyl-li-ethylcarboxylate- Do. p g

j DYIZZO 0H0 Vulcan fast red G Fig. 80, p. 407"-.. o-Dianisidine bis4-(azo-1-p-tolyl-3methy1-py1'azolone) Do. I,ermaneut red F 4RH 1 Fig.77, p. 405..-" 1-(p-chloro-o-tolylaz0)-2-naphth0l3-amido-n-(p-chloro-o-meth- Substituted phenyl-naphthyl-Y y1 benzene). toluidine azo pigment. 'Permanent'rcdF 4R' Fig. 76,4,05... Ring structure similar to that of pigment (14) Do.Clgloronitroaniline red Fig. 75, p. 404 rln Do.

OTIGI'. Nitroaniline red toner..- Fig. 73; p. to? dn Do. :Toluidine;maroon toner- Fig. 82, p. 408 do Do. Ni troanisidine maroon,.Fig.-84,.p.409 do Do.

0116!. Indanthrene blue ;Kzgfiers tOrganicN-N-dihydro-1,2,1,2-dianthraquinone phenazine Dianthraquinone dye. emlsry I). 401,4th'Edition. 21...-. lngziitl tlihieneorange Fig. 126, p.430.... Bromo-anthraqulnone dye.

l Unlessotberwise indicated, references tostructure may be found in J.J. Mattiello, Protective and Decorative Coatings, V. 5 Chapter 4 (Johnwileyendsons, 19 26).

ths...

Representative of the soluble pigments which may be employed are thevarious indigo dyes such as Ciba Yellow 3G, Brilliant Indigo 4B, CibaGreen G, Ciba Violet A, Helindon Orange R, etc., the Alizarine dyes suchas Alizarine Cyanine Green, Alizarine Blue, Alizarine Orange and thequinoline dyes such as Chinoline Yellow. These dyes are described andmethods of preparation are given in Organic Chemistry, Fieser andFieser, second edition, pages 907, 910-912 and 916-918.

The pigment is dispersed in the vehicle using any of the conventionalblending techniques which are employed in the ink and paint industry.Thus, the pigment and the vehicle may be blended in a pebble mill, ballmill or any type colloid mill or the dispersions may be effected byusing a three roll paint mill. The concentration of the pigment in theoil will depend on the intensity of the color desired, the desiredthickness of the ink mark and on the desired density of the inkpreparation. Concentration of the ingredients is also based on theparticular marking process which is to be employed, e.g., silk screen,intaglio or stamp. Concentration generally will be between about 1 andabout 50% of the pigment in the vehicle, while a preferred concentrationis between about 5 and about 20%. Ink concentrates may contain up toabout 70% pigment.

The colorant composition of this invention also containstrichloroethylene, which not only serves to regulate viscosity of thecomposition, but also assists in penetrating the solid polymer surface,permitting more effective deposition of the incorporated colorant orpigment in or below the surface of the solid polymer. The vehicle, i.e.,the liquid polymer of trifiuorochloroethylene, assisted by thetrichloroethylene, apparently either volatilizes or diffuses through thesolid polymer, leaving the coloring pigment as a concentrated mass in orbelow the surface. Although the colorant composition can contain widelyvarying amounts of trichloroethylene, it usually constitutes 5 to 75weight percent of the colorant composition, preferably 30 to 50 weightpercent. Trichloroethylene is generally added to the colorant-vehicleblend in an amount within the above ranges which depends on theviscosity desired.

The ink composition may be applied to the cold surface of the plastic byany of the conventional printing or marking processes such as flowing,dipping, stamping, etc. The marked plastic is then heated at atemperature between about 170" C. and the decomposition temperature ofthe plastic, usually between about 170 C. and about 375 C., for a periodof time between about one second and about 30 minutes to set the ink.Preferably, the marked plastic is heated at a temperature between about190 C. and about 200 C. for a period of time between about one andminutes. The trichloroethylene is preferably allowed to evaporate beforethe heating operation is begun. In the marking of wire coatings rapidsurface heating is usually required and thus air or gas temperaturesbetween about 300 C. and about 375 C. may be necessary to set the ink ina short period of time. Any source of heat can be used in theapplication of these inks such as a hot blast of air or an inert gas,oven heat and infra-red heat.

A preferred embodiment for coloring wire insulation involves thepositioning of spray guns about the circumference of the plastic coatedwire to deliver trichloroethylene containing colorant composition to thesurface of the plastic after it leaves the extrusion die and beforequenching. The hot plastic coating being sprayed after it emerges fromthe die is preferably at a temperature above its transition temperature,usually above 170 C. for perfluorohaloolefin copolymers and above 210 C.for perfluorohaloolefin homopolymers. A frequently used die temperaturerange is 300 C.-355 C. If the plastic 6 coating is sprayed when belowthe transition temperature, subsequent heating above such temperaturewill serve to set the colorant.

In order to illustrate this invention, the following examples arepresented. Example 1 is representative of ink formulations which wereprepared by dispersing the pigment in the oil in a three-roll paint milland subsequently adding the trichloroethylene, and which weresuccessfully employed in marking perfiuorochloroolefin polymers. Theseexamples are offered for purposes of illustration and are not to beconstrued as necessarily limiting the invention.

Example 1 Ten parts by weight of phthalocyanine green and parts byweight of trifluorochloroethylene telomer oil were dispersed in athree-roll paint mill. Ten parts by weight of trichloroethylene wereadded to the dispersion. The colorant composition was then spread on anink pad, and printing was done with rubber stamps on 5 milpolytrifluorochloroethylene film. The printed film was heated for twominutes in an oven set at 190 C. to develop adhesion. The printed markwas stable, did not smudge or crack, was permanent, and did not offsetwhen the surface was reheated.

Example 2 Three spray guns (Paasche multihead air brush, type AURTF with#1 needle air cap) were set at degree intervals around the circumferenceof the plastic coated wire emerging from an extrusion die, to deliver acolorant composition to the plastic coating. The spray nozzles werepositioned at such a distance from the moving wire as to permit someoverlapping of the spray patterns of each nozzle, thereby to insureuniform circumferential distribution of the colorant composition. Lowcolorant cost eliminated the need for reusing the overspray, andrecovery of the overspray was not therefore attempted. The coloringoperation was carried out at wire speeds of 110 to 180 feet per minute,but speeds in excess of 200 feet per minute, such as 250 feet perminute, have also been used. Wire used was #22 AWG 7/30 silver platedcopper conductor, and the colorant composition used was as in Example 1.The temperature of the extrusion die was approximately 640 F. Theplastic coating consisted of a blend oftrifiuorochloroethylene-vinylidene fluoride copolymers and includedthose with respective monomer mol ratios of 96/4, 75/25, and 50/50 in acopolymer weight ratio of 90:7 :3 respectively. After the colorantcomposition was sprayed on the surface of the hot plastic coating, thecoated wire was quenched. The colored wire thus produced was stable, didnot smudge or crack, and the coloring was permanent.

Other colorant compositions within the scope of the above disclosuresimilarly produced a colored wire coating with the same outstandingproperties.

It is also within the scope of this invention to apply the coloringcomposition to the hot plastic by any of the methods known to the art,such as by spraying, flowing, by use of an enclosed colorant bath, etc.Other modifications and changes will become apparent to those skilled inthe art, and the matter contained in the above description is to beinterpreted as illustrative only.

We claim:

1. In a process for coloring the surface of perfiuorohaloolefinicpolymeric material the improvement which comprises applying to saidsurface a colorant composition consisting essentially of between about 1and about 50 weight percent of a colorant, between about 5 and about 75weight percent of trichloroethylene, and a low molecular weighttrifluorochloroethylene polymer having a softening point below C., andsetting said colorant at a temperature above about C. and below the de-5. A colorant composition consisting essentially of atrifluorochloroethylene polymer having a softening point below about 150C., between about 1 and about 70 weight percent of a colorant, andbetween about 5 and about 75 weight percent of trichloroethylene.

6. The colorant composition of claim 5 in which thetrifiuorochloroethylene polymer is a liquid.

References Cited in the file of this patent UNITED STATES PATENTSBrubaker Feb. 5, 1946' Miller Apr. 14, 1953 Conner Apr. 19, 1955Barnhart et al June 19, 1956 Rodman Dec. 11, 1956 Smith Dec. 18, 1956'Smith Dec. 18, 1956 Kohring Aug. 20, 1957 Roberts et a1. Feb. 11, 1958FOREIGN PATENTS Great Britain .1. July 8, 1954 OTHER REFERENCES TheCondensed Chemical Dictionary, 4th edition, 1950,

page 571.

